I'm starting a tunnel ram PFI conversion sometime in the next couple of weeks and thought I'd share a couple of pics here.
The engine is a mostly stock oval port 454, with a mild Voodoo cam (60202).
The intake is an Offenhauser oval port tunnel-ram with a single carb top.
I'm about to cut the top off the plenum and start fabricating a new top. The throttle-body is an 85 or 90mm from a Q45. The TB has a nice progressive cam and roller setup similar in function to some progressive secondary Holley double pumpers.

This was just a quickie foam-board/hot glue mock-up. I already know its really crooked and off center. I think I'll probably do the final aluminum version straight and symmetrical
I'll post some progress pics here soon.

 

I probably would point that throttle body down some to help with hood clearance and lining it up with an intake tube. Just a thought

 

I don't have to worry about that. This is going in my dads 53 chevy pickup, I'm actually thinking about making it an inch taller. I was going to do double downdraft throttlebodys, but he wants to turbocharge it later and will have a front mounted intercooler(someday).
Anyhow there's probably going to be about a foot of hood clearance.
I am planning to start cutting this coming weekend, I'll post pics of the conversion.
BTW, one cool thing about these oval port tunnel rams like this is that the outer wall of the runners near the ports is REALLY thick. They apparently use the same outer mold as the rectangle port version. I can probably drill the injector ports without adding any material to the manifold.
Pics to follow next week.

 

ok, its a little past "next week" but I had a brief chance to work on the manifold a few days ago. I cut the top off the plenum and strted to cut an opening on the front. I have the aluminum cut out for the new top, and hopefully I'll get some time to weld it up before christmas.
Anyhow, I wanted to show what the inside of an Offy tunnelram plenum looks like. Please ignore the really messy garage in the background.

 

and three more.

 

Its been quite a while, but I was able to get some time to work on the manifold recently.
I changed the design a bit.
Instead of using an 80mm Q45 throttlebody I'll be machining a custom 2bbl throttlebody. I now have occasional access to a few Brideport mills and Clausing lathes so a custom throttlebody seems rather practical now.

Attached are some images which include the current test mockup in the truck, which has changed to a 54 cab on an S-10 frame, and its my project now rather than my dads, since we are build him a Corvair with a 3800sc and transaxle.

I'm going to cut off about an inch from the front of the plenum and make the backside flush. The welds around the sides and bottom will be built up a little then ground flush and polished smooth, while the weld in the top seam will be left as-is.
Injectors are next.

 

3 more images.
Not too proud of the weld quality on the sides, especially the pass side weld. I started with the top weld then did the drivers side and the the pass side. My Mig was having feed issues that progressively got worse as I went. I decided to stop and finish later with better equipment.

 

nice fab work, i was going to say, having the tb downwards still wouldnt clear a factory camaro hood. im running a dual carb tunnel ram in my 89 rs and its just shy under 13" above the factory hood......lol

 

Just about any other vehicle from what I'm using would be a waste of time to worry about hood clearance. It actually fits under the hood on this with room to spare, but I'll still have 2 openings anyhow for the twin turbo's

 

Coming out real nice, subscribed....

 

i have a weird idea for a small block intake lol kinda like this but not lol

wanna make it for me? lol